Method for comparing dye affinity of textile fibers



2,817,140 METHOD FOR COMPARING DYE AFFINITY OF TEXTHJE FIBERS Mary E. Carter, Norwood, Pa and Gibson 0. Etchison and Howard M. Waddle, Shawmut, Ala., assignors to West Point Manufacturing Company, Shawmut, Ala., a corporation of Alabama No Drawing. Application September 1, 1955,

: Serial No. 532,107

8' Claims. (Cl. 2872) This invention relates to the textile industry, and more particularly to a method for comparing the dye afiinities of different lots of textile fibers.

Synthetic fibers, such as viscose rayon, are produced by numerous manufacturers both domestic and foreign, and are customarily produced and sold in batches or lots. In spite of all effort and care in manufacture, different lots of synthetic fibers exhibit considerable differences in character and properties, Whether produced by the same or different manufacturers. Of particular concern to some segments of the textile industry are differences between fiber lots in their affinity for dye, which often are so great that yarns produced from different fiber lots cannot be used together on the same looms. When this is done, fabrics are produced which when dyed exhibit filling bands, bands of different color which coincide with quill changes in the weaving operation.

Fabric containing filling bands noticeable to the eye must be rejected or disposed of as seconds, and may result in serious economic loss. One method of avoiding this diificulty is the process of tailing out, by which one lot of fibers is run completely out in the mill, and then operation started with a new lot. This procedure, involving complete segregation of fiber lots, is in itself time consuming and expensive, and represents a major interruption in production.

If the dyeing properties of different fiber lots are substantially identical, tailing out is of course not necessary, and filling bands and similar defects will not occur. Manufacturers customarily supply with each fiber shipment a lot number, sometimes called a merge number, and if this number differs from that of a previous shipment suggest that fibers from the two lots not be mixed. The manufacturer may change lot numbers because of a change in raw material source, a change of condition of reaction or other circumstance. Sometimes the manufacturing change is minor, and in many cases lot number changes do not represent substantial changes in dye atfinity. Further, the lot numbers of different manufacturers have no correlation and give no indication of comparative dye aflinities or other properties, so that a shift in source of supply customarily dictates tailing out. One proposal for avoiding the necessity of tailing out, and/ or filling bands in the fabric, involves the formation of fibers of different lots into yarns, and the weaving of fabric therefrom, using first one yarn and then the other as filling in successive sections of the fabric. The test fabric is then dyed and examined visually for filling bands. If filling bands are not perceptible, the fiber lots may then be run together, but if they are perceptible, tailing out must be resorted to. While reliable, this method is also time consuming and expensive. This procedure is further deficient in that when objectionable color disparity is revealed, no reliable indication of the extent of the disparity is obtained.

A principal object of the present invention is to provide a method for comparing the dye aflinities of different lots of textile fibers, of such sensitivity and reliability as to greatly reduce the frequency of tailing out in textile operations, while avoiding fabric rejection due to uneven dyeing.

States Patent Patented Dec. 24, 1957 A related object of the invention is to provide a method for comparing the dye affinities of different lots of textile fibers, adapted to furnish a numerical or ratio indication of the disparity therebetween, which may be utilized to control the blending of fibers to avoid tailing out and for other purposes.

Other objects are to provide a simple and quick method for comparing the dye afiinities of different lots of textile fibers, which method exhibits consistent and accurate reproducible results. Further objects will be in part evident and in part pointed out hereinafter.

According to our invention, representative small samples of different lots of fiber are selected, and dyed under identical conditions. Preferably, the samples are dyed simultaneously, in the same bath. According to the preferred procedure, one or more one-gram samples of each of two lots of fiber are selected and weighed out. The samples may be combed to separate and align the fibers thereof, and each is then placed in an individual section of a common foraminous basket. Conveniently, the basket is divided into eight sections, to accommodate four sample pairs, which may represent one or more pairs of fiber lots to be compared. Each sample in its basket section is weighted down with a screen weight.

An 800 milliliter dye bath is prepared containing a suitably soluble and stable dye such as 0.04 gram Calcomine Sky Blue FF Ex. Conc. and four grams sodium chloride. The bath, in a 3.5 liter stainless steel container, is heated to approximately 97 C., and the basket then inserted quickly. The basket is then moved up and down in the dye bath fairly rapidly, preferably by mechanical means, the stroke length being about 4 inch and adjusted so that the fibers just emerge from the bath at the top of each stroke. The dyeing is continued for ten minutes, the temperature of the bath being maintained at a temperature between and 100 C. In this manner, identical dyeing of the fiber samples is assured.

When the dyeing is completed, the fiber samples are rinsed well, and individually squeezed, pressed between paper towels, spread apart and dried loose at room temperature. The dyed and dried samples are then individually combed by hand to parallel their fibers.

Thereafter, the Well known principle of fiicker photometry is utilized to compare the colors of the dyed samples of each pair. While various photometric devices suitable for the purpose are well known and may be employed, we prefer to use the Color-Eye, manufactured by Instrument Development Laboratories, Inc. of Needham Heights, Massachusetts, which apparatus is illustrated and described in United States Patent Number 2,686,452, issued August 17, 1954, to Edward P. Bentley. Devices of this type include an integrating sphere having spaced openings, to which a standard material and another material of similar color may be presented. A light source is provided inside the sphere, and light reflected by the two samples is focused by an optical system alternately onto a sensitive photoelectric cell. The output of the photoelectric cell actuates a meter, which indicates the color contrast of the two materials in both magnitude and direction. That is, the meter indicates the ratio of the amount of light reflected by the sample to the amount of light reflected by the standard, usually in terms of percentage. The theory and structure of flicker photometers being well understood, and not a part of the present invention, more detailed description is unnecessary.

To simplify the process and obtain uniformly consistent results, we have found it essential to rotate the dyed fiber samples presented to the flicker photometer. This expedient, it is found, not only avoids all necessity for repetitive testing and averaging, but also effects greater accuracy. For this purpose, the fiber samples may be mounted in small disc-shaped holders, and these holders presented to the photometer sample openings While being rapidly rotated on their axes. Small electric motors turning at 1675 R. P. M., for example, may be utilized to rotate the samples.

The diverse dyed samples are illustrated in the photometer with diffuse daylight, of the nature of the International Commission of Illumination Illuminant C (about 6500" K.). Light reflected from the rotating samples is gathered by the optical system of the photometer, and focused alternately onto the photoelectric cell in the well known manner. Commonly in flicker photometry the reflected light is broken down into the tristimulus primary colors established by the International Commission of Illumination, corresponding to X-amber, Y-green and Z-blue, and the primary color components are contrasted separately and sequentially. We have found that reflectance comparison of a single tristimulus color may be relied on in our method, and that the X- amber color value is most sensitive and significant. That is, when comparing samples dyed as described above, reflected light having a frequency in the vicinity of 600 millimicrons indicates maximum color difference, and may be utilized exclusively. Accordingly, the photometer may be employed with an X-amber filter always in the light path, and further contrasting of the other primary colors is unnecessary. Using other dyes, reflected green or blue light may be most significant, but light of one of the tristimulus colors will usually suffice.

The flicker photometer indicates the relative intensity of the beams of light focused alternately on the photoelectric cell, as a ratio. That is, the light reflected from the sample exposed at the standard opening of the device is taken as unity, and the meter indicates the intensity of the light reflected from the sample exposed at the sample opening as a percentage of the standard light beam. Accordingly, if the indicated ratio exceeds unity or 100%, the sample exposed at the sample opening of the device reflects more light than the sample exposed at the standard opening, indicating that the sample exposed at the sample opening has absorbed less dyestuff, and is of lighter color and/or shade. This sample, then, would have a lesser affinity for the dye than the sample exposed at the standard opening. If the indicated ratio is less than 100%, then the sample exposed at the sample opening reflects less light than the sample exposed at the standard opening, has absorbed more dyestuff and is of darker color or shade. The numerical difference between the photometer indication and unity, or 100%, may be considered the color difference, or the difference in dye absorption or dye affinity between the two samples. The tables following illustrate repeated color comparisons as described between three pairs of different fiber lots. In each table, all odd numbered samples represent one lot, and all even numbered samples represent the other lot.

Samples: Table I Photometer reading 1a2a 102.0

Bib-41) 100.9

1a2a (recombed) 101.9 la2a (recombed) 101.7 7a8a (recombed) 100.5 7b--8b (recombed) 99.5 7b-8b (recombed) 99.7 3a4a (recombed) 101.4 3a-4a (recombed) 101.4 5a6a (recombed) 101.6 5a6a (recombed) 101.4

Average 100.99

4 Table 11 Samples: Photometer reading 1--2 105.3 3 4 104.3 5-6 103.8 78 104.3 16 104.4 1-4 105.4 1--8 105.0 Average 104.6

Table III Samples: Photometer reading 1a--2a 107.2 3a4a 108.0 5a6a 109.0 7a8a 106.0 1b-2b 108.6 3b-4b 107.8 5b6b 108.7 7b8b 109.5 1a4a 108.2 5a2a 107.9 3a6a 108.7 7a4a 107.0 Average 107.4

The foregoing tables illustrate three different dye aflinity comparisons, in which the compared fiber lots have respectively a very small color difference (1% a medium color difference (4.6%) and a large color difference (7.4%). From these color measurements a standard deviation value may be calculated, and is found to be 0.78%. The extremely low deviation indicates excellent accuracy and consistency.

In the manner described, the dye affinities of different lots of textile fibers may be compared merely by selecting a single sample of each, dyeing the samples under identical conditions as set out above, and then determining the comparative light reflectance of the dyed samples by a single exposure to a device such as a flicker photometer while rotating the samples, using diffuse daylight for illumination and utilizing only the reflected light of a single primary color. Of outstanding importance, a numerical value corresponding to the color difference is derived, variously useful and more significant than, for example, mere disparity such as may be discerned by visual inspection.

For example, we have found that fiber lots exhibiting a color difference of 1 or 2% by the present method may be run together without danger of filling bands or similar defects in dyed fabrics produced therefrom. A color difference of 3 to 5% indicates the possibility of difficulty, and a color difference of 6% or more indicates positive likelihood of easily perceptible and objectionable filling bands in the final fabric produced. The numerical color difference value between lots may be advantageously used in blending fiber lots. We have discovered that when running a mill on one fiber lot, which lot may then be taken as standard and assigned a reflectance value of 100%, it will always be permissible to continue operation with another lot having a comparative color value differing therefrom by approximately 2% or less, either plus or minus. Another lot having a color difference of, say, 4% might be unsuitable to run in without tailing out, but such lot might be blended in equal proportions with still another lot having a color difference of 1% or less, whereby the blended lots would exhibit a tolerable color difference. In changing lots of a fiber which constitutes only 20%, for example, of a blend a greater difference in dye aflinity may be tolerated than in the case of a fiber constituting 60 or of a blend. To utilize a fiber lot exhibiting a color difference of 11 or 12%, on the other hand, would necessitate either extensive blending or resort to tailing out. The samples compared according to the invention need not, of course, be fibers of one kind, or one lot. The

- compared samples may in themselves be blends, of different lots or of different fibers, in any proportions. The wide range of utility of the process will accordingly be evident.

Calcomine Sky Blue FF Ex. Gone. is a highly suitable dye for use in the process, particularly with viscose fibers, due to its ready solubility, stability and sensitivity. That is, it is convenient and effects relatively great color diflerences. It will be obvious that other dyes may be used. Calcodur Blue 4 GL 160%, for example, would be approximately equally useful. In competitively dyeing fibers of nylon, orlon or other composition, still other dyes may be most suitable. Our process has been thoroughly proven in practice, and when utilized to control purchasing of fibers, fiber blending and the like permits con tinuous mill operations for long periods of time, without tailing out and without product rejections due to filling bands and similar color disparities.

It will thus be seen that there has been provided by this invention a method in which the various objects hereinbefore set forth, together with many practical advantages, are successfully achieved. As various possible embodiments may be made of the novel features of the above invention, all without departing from the scope thereof, it is to be understood that all matter hereinbefore set forth is to be interpreted as illustrative, and not in a limiting sense.

We claim:

1. A method of controlling textile operations wherein different lots of textile fibers are employed comprising the steps of dyeing fiber samples of different lots under identical conditions, rotating the dyed samples, illuminating the rotating samples with diffuse light, comparing the light reflected by each other sample with the light reflected by :one of the samples which has been selected as a standard to derive a ratio indicative of the relative dye aflinities of said samples, and thereafter combining the lots in fabric production in accordance with said ratio.

2. A method of controlling textile operations wherein different lots of synthetic fibers are employed comprising the steps of dyeing fiber samples of different lots under identical conditions, rinsing and drying the dyed samples, rotating the dyed samples, illuminating the rotating samples with diffuse light, comparing the light reflected by each other sample with the light reflected by one of the samples which has been selected as a standard to derive a ratio indicative of the relative dye aflinities of said samples, and thereafter combining the lots in fabric production in accordance with said ratio.

3. A method of controlling textile operations wherein different lots of textile fibers are employed comprising the steps of dyeing fiber samples of different lots under identical conditions, rinsing and drying the dyed samples, rotating the dyed samples, illuminating the rotating samples with diffuse light, and comparing the light of a single pri' mary color reflected by each other sample by flicker photometry with the light so reflected by one of the samples which has been selected as a standard to derive a ratio indicative of the relative dye aflinities of said samples, and thereafter combining the lots in fabric production in accordance with said ratio.

4. A method of controlling textile operations wherein different lots of synthetic textile fibers are employed comprising the steps of dyeing fiber samples of different lots under identical conditions, rinsing and drying the dyed samples, rotating the dyed samples, illuminating the retating samples with diffuse light, and comparing the amber light reflected by each other sample by flicker photometry with the light so reflected by one of the samples which has been selected as a standard to derive a ratio indicative of the relative dye atfinities of said samples and thereafter combining the lots in fabric production in accordance with said ratio.

5. A method of controlling textile operations wherein different lots of textile fibers are employed comprising the steps of dyeing fiber samples of different lots under identical conditions, rinsing and drying the dyed samples, paralleling the fibers of each sample, rotating the dyed samples, illuminating the rotating samples with diffuse day light, and comparing the amber light reflected by each other sample by flicker photometry with the light so reflected by one of the samples which has been selected as a standard to derive a ratio indicative of the relative dye affinities of said samples, and thereafter combining the lots in fabric production in accordance with said ratio.

6. A method as defined in claim 5, wherein said samples are dyed with Calcomine Sky Blue FF EX. Gone.

7. A method as defined in claim 5, wherein said textile fibers are viscose fibers, and wherein said samples are dyed in a bath containing .05 gram Calcomine Sky Blue FF Ex. Gone. and 5 grams sodium chloride per liter for a period of approximately 10 minutes, the bath being maintained at a temperature within the range of from about C. to about C.

8. A method of controlling textile operations wherein difl erent lots of textile fibers are employed comprising the steps of dyeing fiber samples of two different lots under identical conditions, rotating the dyed samples, illuminating the rotating samples with diffuse light, comparing the light of a single primary color reflected by one sample with the light reflected by the other sample which has been selected as a standard to derive a numerical value indicative of the dilference in color of said dyed samples in both magnitude and direction, and thereafter combining the lots in fabric production in accordance with said value.

References Cited in the file of this patent UNITED STATES PATENTS 1,971,317 Sheldon et a1 Aug. 21, 1934 2,020,281 Stone et al. Nov. 5, 1935 2,022,327 Sheldon Nov. 26, 1935 2,686,452 Bentley Aug. 17, 1954 

1. A METHOD OF CONTROLLING TEXTILE OPERATIONS WHEREIN DIFFERENT LOTS OF TEXTILE FIBERS ARE EMPLOYED COMPRISING THE STEPS OF DYEING FIBER SAMPLE OF DIFFERENT LOTS UNDER IDENTICAL CONDITIONS, ROTATING THE DYED SAMPLES, ILLUMINATING THE ROTATING SAMPLES WITH DIFFUSE LIGHT, COMPARING THE LIGHT REFLECTED BY EACH OTHER SAMPLE WITH THE LIGHT REFLECTED BY ONE OF THE SAMPLES WHICH HAS BEEN SELECTED AS A STANDARD TO DERIVE A RATIO INDICATIVE OF THE RELATIVE DYE AFFINITIES OF SAID SAMPLES, AND THEREAFTER COMBINING THE LOTS IN FABRIC PRODUCITION IN ACCORDANCE WITH SAID RATIO. 